1. Field of the Invention
This invention relates to a heat-sensitive transferring medium of delayed sending type.
2. Description of the Prior Art
Heat-sensitive transferring recording medium has been recently used widely in place of heat-sensitive color developing paper for the purpose of improving storing durability of recording.
The heat-sensitive transferring recording medium is such that heat is applied to the surface of the medium by means of a thermal head so as to melt the heat-melting ink in the heat-melting ink layer and transfer the molten ink to a receiving paper overlying the medium. The once-used ink sheet is not used again, in usual, and in addition, the heat-sensitive transferring recording mediums are expensive, and thereby, the running cost is disadvantageously high.
A proposed improvement is that a substrate of the heat-sensitive transferring recording medium is made in a form of an endless belt and the depleted heat-melting ink due to use is supplemented by coating with a heat-melting ink, but such ink-supplementing device built-in the recording apparatus results in enlarging the recording apparatus, and therefore, the apparatus itself becomes expensive though the running cost is inexpensive.
Another proposed improvement is to employ a heat-melting ink layer composed of a porous layer impregnated with a heat-melting ink. Such heat-melting ink layer can be repeatedly used so that the layer is usually called "multi-type". However, after used once, the heat-sensitive transferring recording medium having the multi-type layer should be rewound and a mechanism for rewinding s necessary.
The present inventors have found that the heat-sensitive transferring recording can be carried out even when the sending speeds of the heat-sensitive transferring medium and the receiving paper (a paper receiving the transferred ink for recording) are not the same (i.e. not the speed ratio of 1:1), but the sending speed of the heat-sensitive transferring medium is slower than that of the receiving paper.
The sending speeds of them can be easily made different by, for example, adding one gear to a conventional winding-up mechanism for heat-sensitive transferring mediums, or changing the number of tooth of gear even without changing the production line of the apparatus, and therefore, the advantage is very large from the stand-points of the production and the manufacturing cost. However, a simply delayed sending of a conventional heat-sensitive transferring medium can not successfully result in good recording since the pressure of the thermal head causes smearing by rubbing.